A small bronze statuette, or weeper, of William of Hatfield can be seen on the tomb of his father Edward III in Westminster Abbey. The figure can be viewed from the south ambulatory. He wears a doublet and hip belt. No coat of arms for identification remains below the figure but it has been recorded as William since the publication of a guidebook to the Abbey in 1600. He was born at Hatfield on 16 February 1337 and died in the July following and is buried at King's Langley in Hertfordshire. So the figure shows him as a youth rather than a child.
See also the entries on the website for William's siblings Edmund of Langley, Lionel of Antwerp, Mary of Brittany and Joan de la Tour. And the small tomb of William of Windsor and Blanche of the Tower.
A photo of the weeper can be purchased from Westminster Abbey Library.